Debugging shinymcp

Inspect inputs and tool groups

Start with the parser and analyzer:

ir <- parse_shiny_app("path/to/app")
analysis <- analyze_reactive_graph(ir)

analysis$tool_groups
ir$inputs
ir$outputs

That tells you whether shinymcp found the same reactive islands you expected.

Inspect bridge traffic in preview

preview_app() now uses the shared host controller and exposes a protocol log in the preview page. Use it to inspect:

• ui/initialize
• tools/call
• ui/update-model-context
• ui/notifications/size-changed

Inspect display payloads

Use format_tool_result() during development when you want to see exactly what the runtime will send back to the host:

format_tool_result(list(
  summary = mcp_result_text("ready"),
  table = mcp_result_table(head(mtcars))
))

For shinychat wrappers, inspect the ContentToolResult directly:

tool <- as_shinychat_tool(card_app)
result <- tool(dataset = "mtcars")

result@value
result@extra$display

Common failure modes

• Input ids do not match tool argument names.
• Large converted groups should really be split into smaller cards.
• Generated conversion tools are still placeholders.
• Rich display works in shinychat, but plain fallback text still matters for other hosts.